What sales advice would you give to your younger self?

When you think back to when you were just getting started selling, do you shake your head in disbelief at how naive you were, or how little you knew? Whether you were a natural or not, you have without a doubt, learned a great deal since then.

If you could go back in time and speak with your younger self, what advice would you give? How much time could you save your former self on his way to success?